Control means for liquid supply systems



Au 27, 1946. -H. E. HOLTHOUSE 2,406,604

CONTROL MEANS FOR LIQUID SUPPLY SYSTEMS Filed June 15, 1942 s Sheets-Sheet 1 H. B. HOLTHOUSE I 2,406,604

CONTROL MEANS FOR LIQUID SUPPLY SYSTEMS Fiied June 15, 1942 3 Sheets-Sheet 2 98: 27, 1946- H. B. HOLTHOUSE 4 7 2,406,604

CONTROL MEANS FOR LIQUID SUPPLY SYSTEMS Filed June 15, 1942 3 Sheets-Sheet 3 '6 mlHl may i Patented Aug. 27, 1946 eon-11x01. M-EANS FOWLIQUIDSUPB :sysT Ms Manufa turi s Co ii' ita l 'iin 16 1mm 11 Harry a corporation of Illinois 7 Application June =15, 1942, Serial-No. 1 5141305 gs planes. (curse-28) :1 This invention relates generally to ;control means :15 or: a liquid. su-pplysystem and in particular to :a fuel a system :for apparatus havingia combustion portion :in which the rate of :fuel :feed to the combustion portion is controlled ;in:re,Spnse -t 0 the heat radiated therefrom.

' ;-An :object of :this'invention is -togprovidegimproved heat responsivemeans-foroont'rolling the rate ;of liquid flowinra:liquid; supp1y;'system: 7

,Another :object of athis invention is to PEQY SIe a protective system for zQo j lfolliiflg the rate of :fuel feed to thecombustion portion of apparatus of internal combustion itype in response :to the heat radiated "from such combustion portion.

A "further object .Of :this invent on -i :t Wary the rate-of-fuel .feed-;to;the;eombustion portionof heating tapparaitus relative :to the gheat =;1'adiai ,ed. from the combustion :portion.

Stilhanother; object of this-,i-nVentiQn; is to 0911- -tr01 the rate of ifue1:fe'ed';t0,11 1 1 mb l$i ;P9 vtion of :air :heating apparatus in -;res p onse to ,the temperatures .-of .therair to joe heated and -,of the heat radiated from :the icombustien :nort1en.

A :featurelofthisiinvention isjoungi in-- the;prpvision oflafuelisupply system inol-uging a purqp .and:;fue1 iline for:apparat.us;havil; acorn portion, in which :the y te gsrerrange meats-exchan e relation-with thet bpst on e .tienzandmas;.arheatab ma whie A ;tive :to {the samounteof f el ftowiryg gtherethrou'gh smastotran fe zhea .tasue -ifue Qmheat x o the-syst m, gab ve ;-a-; rta-in mpe a u e-a; b 7: lock condition is producedin, the .whi(:h e- Aduces -the ;rate ,of fuel feed t.o-:.th,e ,conibu'stion portion. Another feature of this invention is found in the provision of a fuel supply jsystem for 'ir'heatheating :of the air .;c ircul ate'd tfibQiit ,the

above-a normal coolingitemperatlire'the'gteinp .tureof the'punip is increased jto'azvalue; lvaporizes the fuelitherIein-so th'ft' a v por condition-is produced inthe -plinl' l'pf h..1 duoes 'the rate of, fuel .feed -to theaeoinhust on poi tion.

:Further objects, ,-features -alnd advantage gar thisinventionwillbeeomep-appaizent fro the o1 .low-ing: description when taken innconneetionlwith th -acco n g:drawinss in-whi h:

:Fig. 1 is rspect-ive wiew -ef tan -air he tin apparatus embody-ins th u l 3 supply 1 ystem-0 this invention; I I

. f ig :Zisei an v rs isee i na v w o t ee p menus or i-E ;1 w th th comb s :Portion :thereof shown .in development for the purpose of .i lar Fig.3is,a.transverseseotional View of the comlbust ion pqttmnofthe heating-apparatus vas seen lone :the lin i Ha 4 is }.a longitudinal sectional view ,of the unipsinelhded as apart of .the fuel supply is I to pfthis' i' jention;

v Fig. 15 "is a transverse sectional view as seen an s sth r e 5 P a and "F g. I6 illustrate diagrarnmatioally 1a control circuit for the sheaterapparatus n Fig 1 and 2, illustrated in fthe drawings as "heating apparatus for' controlieedp fleq u tionpo i n se to the heat radiated from z 'q rt e Thejh a in ia ara u .4 v hu t q'n. mpart entiipr t e ce ibustlo in. uandi ni' a ijcem r ment "af ali ed @9 1 sea 1 th mbus iQ c a "mam i sio as to th in a h a exchan r atien ll w'i h- I QGa Q withi'nih ,I g a ifial mrtm'e t Qandaglapted to be heated therein is a th .eembu t e o t in. udm 'a'i ie inumn an iai ie JJ n "Them abl'e ass of the 'systernis such that the heat th efr .i tra st r e t t e fl itherj '{Ifhe air to ,be heated initially flows it ro hth lmechaniea ieqm art n eoe t s; thei ein priorv to; passing in a heat exchange tien w th:th' .eombust on; or n. wOn heating a .t .-L .1. e a ov ano je j nste a ipe ture. i s: i in tunetie fi u dte el ,en,t. withjani ncr ase: im -h t r d d th ieombustie etno tienih virtue o ch ;crea'sedtemperature;;to provide in allforaheath ffilfi .iSUPPlYlSY tGm a v a o l per. m empe atu tTh ss e e ion' a e'r ed relativeutogthe heating-of thQfllGl system, s 1 thefflow of air mo -be heated be entirely d- ZIhe increase gin the' ten perature of the -fuel .sYS Lm Leb' Y J t orma .i e t ns t er effects a vaporization of'theflfuel in thepurn-p t o produeea vapor look condition therein which reduce the rate of fuel 'feed 130' the eo mbustion "portion and in a turn the heat generatedtherein.

ge n n dhea iae: fz h u l s em ab mal Qperatingfteinperature the vapor lock Isa nh izeidni iliue i n ea t (a po n which th A v i01 JQ "th L qmb l' ti n P0 is" practically stopped. This arrangement of "the .iueltsupp ly-r s t m relat v t it e ssioe ja e i ee plate as.

bustion portion thus provides a protective system which acts to eliminate. an overheated condition of the combustion portion and to retain the heat radiated therefrom substantially uniform.

Referring to Figs. 1 and 2 the heating system of this invention is seen to include a housing H] which is divided longitudinally thereof over substantially its entire length by a partition member I l to provide a mechanical compartment l2 and a heating compartment. Within the are thus all located within the mechanical comheating compartment is a substantially cylindri-..

cally shaped combustion chamber l 3, shown in end by a cover plate It and at its opposite end by the bottom It of a substantially dish-shaped member l1. air supply chamber I8 which is in axial alignment with the combustion chamber I3.

The combustion chamber l3 is divided longitudinally thereof into four axially extending but connected passages Illa-49d by a partition member 2| of substantially X-shape (Figs. 2 and 3 The combustion chamber inlet 22 and outlet 23 are formed in the bottom portion l6 of the member I! in communication With-the passages Ida and IBd, respectively. Located within the inlet 22 is an air andfuel mixing means, indicated generally as 24, which is extended within the air supply chamberflld. The outlet 23 is provided with a tail or exhaust pipe'assembly 26 extended into the air supply chamber l8 and outwardly therefrom through the end 2'! of the housing member B;

The outer wall or body portion of the com-- bustion chamber I3 is integrally formed with alternately arranged peripheral portions 23 and doubled fin portion 29, which are angularly spaced about the combustion chamber and extended axially thereof. The side portions of the partition member 2! are located within certain ones of the fins 29 and retained therein in a fixed position relative to the combustion chamber body portion by Welding or like means. The

fins 29 have a sleeve 3! positioned about the outer ends thereof so as to form an annular passage 32 about the combustion chamber l3 forair to be heated. f

The air to be heated is admitted into the passage 32 through an inlet 33 connecting the passage with the mechanical compartment [2 and is circulated throughthe passage 32 by a fan 34 located within the compartment l2 and mounted on a shaft 36 .of an electric motor 31 (Fig. 2). The compartment l2 and airpas'sage 32 are separated from the air supply chamber l8 by a sealing or partition member 38 extended transversely of the housing l0. From Fig. 2 it is seen that the air supply chamber i8 is defined by the dish-shaped member l1, thepartition member 38, and the end 21 of the housing ill. Air circulated by the fan 34 is thus confined to travel within the compartment I2 and passage '32 and is discharged from the passage through an outlet 3-9 which is connected to a space to be heated.

The supply chamber is receives air from a fan 1 4| located therein and mounted onthe motor shaft 38 which is journalled in the partition An inlet 42 for the fan 4| is provided inthe housing end 21. It is seen, therefore, that the fans 34 and 4| are operated by a com- The member I! defines in part an i mon electric motor 31 and are mounted directly partment l2, which is provided with an inlet 48 for supplying either fresh or recirculated air to the fan 34 for delivery to the air passage 32.

The pump 43 (Figs. 4 and 5) includes a cylinder lil of tubular form which is operatively associated with a tubular piston ll of elon ated construction. Th cylinder 10 is provided in a suitable non-magnetic material, such as brass, while the piston is provided in a magnetic material, such as iron, movement of the piston in one direction being eifected on energization of a solenoid '12 which is mounted about the cylinder 10, the piston ll operatingas a solenoidal c'ore.- Fluid enters the pump at the cylinder end 13 and is discharged therefrom at the cylinder end 74, the piston being operable substantially between the cylinder ends. The flow of fuel through the cylinder ends 13 and 14 i controlled by valve structures 16 and TI, respectively,

"while the fuel flow through the tubular piston "H is regulated by a valve structure 18 carried in one end thereof. All of the valve structures are of a substantially similar construction so that similar numerals of reference are used to designate like parts. Thus as shown in Figs. 4 and 5 each valve 56', Ti and 18 includes a disc member T 9, normally retained on a corresponding seat portion 8| by a corresponding spring 82. All of the disc members 19 are lifted in the same direction away from their corresponding seats -in response to the fuel pressures acting thereon.

In the operation of the pump the piston 10 is moved in one direction, namely, to the left as viewed in Fig. 4 by the magnetic action of the solenoid 12. A return movement of the piston 10, towards the right, is obtained by a spring 83 which is=located in an expansible inlet chamber 84- formed between the valve structures 76 and T8. The solenoid I2 is selectively energized by the action-of the breaker assembly 44. On movement of the piston ll to the left, the chamber 84 is contracted to increase the pressure of the fuelin such chamber. This increased pressure seats the disc 19 of the ,valve assembly 16 to prevent any flow of fuel outwardly from the pump inlet, and lifts the disc 19 of valve assembly 18 to permit fuel from the chamber 84 to flow through the tubular piston ll into an expansible outlet chamber 86 formed at the cylinder end 14, as indicated by the dotted line 81. On deenergization of the solenoid movement of the piston ll! toward the right, as produced by the spring 83, effects a suction pressure in the inlet chamber 84, due to its being expanded, whereby the valve structure 16 is opened to permit fuel to flow into the inlet chamber 86; the fuel admitted. to the chamber 84 being at substantially supply line pressure. The fuel in the outlet chamber 86 is compressed due to such chamber being contracted, withthe increase in pressure closing thevalve structure 18 and opening the valve structure T! to discharge the fuel from the pump. On reenergization of the solenoid the cycle of piston operation is repeated.

"i and'ab'out'the fuel nozzle '48. entering the mixing chamber'53' 'is'heated-to at least a fuel vaporizing temperature for'intimate 'mixing with the air in such chamber by thefunc- 'tion of the heating unitBI, the heat from which equalizing eats-eel 5 i wa e flfii til .6 when .1 o'pen'in the d"r"c'tion 'of fuel new and are loperable response to the fuel pressuresfproduced in the expansible chambers 84 and "86 bythe reciprocatingactionjofthe piston 1| in the cylinder 10. Thi's action of the piston and disc members provides for a successive. moving "of the fuel through the pump, the fuel first being admitted into the inlet chamber Mfthrough the ve-w n on movement "of jthepis't'on ""ll toward the right, then passed through the valve 18 to the .chamber fl fi'onfmovernent of the pistontowjard the l'eft,and finally ejected from the "pump, through'the v rve II on meveinente the piston towajrd the right. It is 'tob'e noted'that the movementof thepiston ii Itowardjhe right provides for the fd'rawingof Y fuel into the chamber fat "and the "discharge of theme from the-chamber at some}; thesuction actionofthepuinp occurs concurrently with its ejection action.

I The air. and fuel mixing the-ens, previously mentioned, includes a v "substantially tubular "shapfedhousingme'rriloer 5| which is cl o'sed'ation'e end and open er the end 52 thereof withfthe passage [9a. A mixingchamber 53 isflo'c'ated at the closedndof the'casing 5|, :and is separated from anequalizing chamber 54 by a plate member -5i; having perforations'5'lytherein. The equaliziI lig chamber '54 in turni s bothf'defi ned andseparated'from the combustion'cham'ber passage 19a by a heat insulating plate 58 havingperforations 59 therein Extended substantially axially throughthe easing 5l and projecting outwardly "from the closed end thereof is a combination heating an-d'igniting unit 6| includingaresistance coil 62 supported in a spaced relation within a heat-conducting tube 63 composed of copper or like material. :The'casing 5| and partition plate 56 are provided'in a heat conducting material,

such ale copper or the like, and are in' thermal connection with thecombination unit 6| so as toreadily receive heat therefrom. The-combination unit 6| isadapted to heat the air and 'fuel mixing means 24 to'at least afuel vaporizing "temperature to facilitate-the mixing together of the air and fuel admitted therein, an-dto-ignite such mixture for burning within the combustion chamber 13. I

The fuel delivered to the fuel injection nozzle "48 bythe pump 43'is'directed into themixing chamber 53, the'fuel nozzle'being located-within the air supply chamber and mounted directly-on the casing 51 at the chamber 53 (Fig. "2) -A-portion of the'air'formixingwith the fuel enters the nozzle'fl'fl" through portsfi l therein and travels with'this fuel into the mixing chamber 53. Furfther air is admitted directly into the mixing chamber 53 through apertures 66 in the casing The fuel thus -istransferred tot-he casing5l and plate 56 in thermal connection therewith. Mixing is facili- "tated by thetu'rbulence of'the'air in the mixing fohamber. Thisvaporous mixture passes into the chamber "54 through the apertures 51 'i'n-the plate member 56. The equalizing chamber in conjunction with the insulating plate 58, which retardsythe mixture flow through the condition- "ing unit -24, acts to reduce turbulence in the "mixture and to'disperse the mixture substantially niform Y O$ "th .e iirq.Q@9Eli;lh casing 5| so that a mixture of substantially uniaintesteheieetehshee pessesne uehsleeperi'notor 51 'and "2361152 of thec'o'mbination electrical unit 61 areseri'es "connected in a common {circuit whieh from thefbatt'erytt 'includesconductortfi, co'ntrol swit'ch e1, co'nductor 92, meter at, eon- ,{ductor 9's, coil t2 and 'afgrou'nd eeh'heetieh e i.

The circuit'of the pump te'fjr'om the hetteryts includes conductor '89, control switch FH, conoluctor 86, the breaker assembly 14,. conductor 91, the pump 43a'nd "aground 'co'nn'ection iifi. Thus on opening'and'clpsing'of the control switch iii the motor 3 7, e01 "5'2 and pump' l-3 are all operated and stopped together. I

During the "operation of the heater apparatus 'it is desirable, of course,'that thec'o'mbustion-poi tion be operated to "deliver a substantially uniform heat "so that overheating thereof, resulting for"some reason from "a failurein the flow of th'e air to be heatedgoran'inc'rease'in'the tempera- "ture of"such"air,"be eliminated. Itis readily apparent that any overheating of the'combustion 'chainberlfi might result in injury or damaget'o 'the'heat'er apparatus as well'as to objects adja- "cent thereto. In order toeliminate these'dange'rs "and to provideat all times for a safe 'oper tern, including the pump '43 and fuel lihe tsgte "provide a protective system which operates in response to" the temperature of the heat of "the combustionportio'n and/or thev heat of the dirculated air t'ocontrol the rate of fuelf'e'ed'to the mixing means 24 and'hen'ce to the combustion portion 'l3.

0n" operatio 'n'o fthe heeterep'earetue the heat from the combustion chainb'erli is transferred oh dlidtln fihd radiation intotlie mechanical :com'part'mfent so as to "heat the parts located These parts are normally cooled bythe passage 'of the 'air to be 'heate'd "which flows through the mechanical compartment [2, as has jben'fullyfxplaihed above. In one commercial embodiment "of the invention the mechanical compartrnntlzis of ale'n'gthbf about twelve inches and has a cross section about four inches square, with the air circulated therethrough hy thefan -34 being on the order of abOutBO-cubic feet-per minute. The pump'AS, inthis emhodi -ment,-has-a heatable mass -'of about one pound with all portions thereof being'substantially heat conducting. "53 is a'rrangedsub'stantially intermediate the sides ef the mechanical l compartment 82 so ast'o be 'As is best shown'in- Fig. '2 thepump spaced a distance of about -2--iriches erserrom the combustion chamber it. This pumpoperates-to "discharge fuel eethe rate of'a'bout six cubic centimeters per minute, which fuel flow therethiough relative to its heatable mass is incapable of cooli'n'g the f ame. 'Inother"wor'ds the mass of the ferred from thepump to the fuel to increase the temperature thereof.

In the operation of the pump 43 a temperature providing for its normal operation is maintained by virtue of the cooling action thereon by the air to be heated. Thus, so long as the air to be heated is supplied at a temperature below a certain value, Which maintains a normal operating temperature of the pump 43, the pump 43 will operate at full capacity to supply fuel to the conditioning means 2 1. However, if for any reason, the air to be heated becomes initially heated prior to its passage into the mechanical compartment H2, or while in the compartment l2, to a temperature which is insulficient to cool the pump to a normal operating temperature a vapor lock condition will be produced in the pump which operates to reduce the rate of fuel feed to the conditioning means 24 and hence to the combustion chamber 13. Since the fuel flow through the fuel system is incapable of retaining the same cooled at a normal operating temperature any changes in the condition of the air to be heated, as above noted, effects a vapor lock in the pump 43.

This vapor lock condition is the result of the H fuel being heated to a temperature such that upon its entering the pump inlet chamber 84 at a reduced or suction pressure therein, fuel vaporization takes place to a degree depending upon its temperature and the suction pressure in the chamber 84. It is well known, of course, that the temperatures of the vaporization points for various liquids are usually given at atmospheric pressure. If the liquid is raised above this tempera ture and the pressure is also increased to retain the liquid in a liquid form, the liquid is said to be superheated, that is superheated relative to its initial temperature and pressure. When liquid in a heated state at a certain pressure is released into a pressure lower than such certain pressure, vaporization takes place to some extent immediately. The extent of the vaporization depends upon the heat available. This occurrence of vaporization is seen, therefore, to depend upon the initial pressure and temperature of the liquid and g the pressure into which the liquid is released. In the present invention vaporization of the fuel results from the heating of the fuel at a pressure in the line, and the releasing thereof into the suction or vacuum pressure of the inlet chamber 84.

By virtue of the degree of vaporization being dependent upon the heat available the fuel supply system can be initially heated so as to provide for a small vapor lock action in the pump and a correspondingly small reduction in the rate of fuel supplied to the combustion chamber. However, should the temperature of the fuel supply system continue to increase above a value providing for such initial vapor lock action, the vapor lock action Will correspondingly be increased to a maximum condition at which all of the fuel is vaporized. This maximum limit results in practically stopping the rate of fuel feed to the combustion portion so as to stop the operation thereof. The reduction in fuel feed to the combustion chamber l3 occurs because of the'fact that the pump, when vapor lock is present therein, functions to pump a combination of liquid fuel and vaporous fuel, with its discharge capacity being reduced in direct proportion to the ratio of fuel vapor to liquid fuel. Thus referring to Fig. 4, on the suction stroke of the piston the chamber 84 is filled with a vaporous and liquid fuel mixture for passage into the outlet chamber 86. However, on compressing this mixture in the chamber 86, the vaporous fuel returns to a liquid state so that liquid fuel is discharged from the pump. Since the liquid fuel in the chamber 86, is of lesser volume than the same amount of fuel which was in a vaporous and liquid state in the chamber 84, the available capacity of the pump is decreased in proportion t the amount of vaporous fuel initiall present in the chamber 84. The pump operates, therefore, to vary the rate of fuel supply to the combustion chamber directly in response to the amount of heat radiated from the combustion chamber so as to provide an automatic fuel control for retaining the quantity of heat radiated from the combustion chamber substantially uniform 'at all times,

Since any overheating of the combustion chamber tends to create a maximum vapor lock condition in the pump the supply of fuel thereto is stopped so as to prevent a prolonged operation thereof in an overheated condition. In the commercial embodiment of the invention above noted the vapor lock action of the pump lags the operation of the combustion chamber relative to the quantity of heat radiated therefrom by a matter of about five or six minutes. The vapor lock action in controlling the fuel feed is thus relatively fast in its control of the heat condition of the combustion chamber.

As Was previously mentioned the reduction in the rate of fuel suppl to the combustion portion I3 is in direct proportion to the ratio of fuel vapor to liquid fuel initially present in the inlet chamber 84. The temperature of the fuel at the pump inlet, therefore, determines the extent to which vaporization will occur in the inlet chamber 84, and hence the amount of fuel pumped to the combustion portion 13. Thus as is noted in Figs. 1 and 2 that portion of the fuel line 46 within the mechanical compartment I2 is extended adjacent the partition wall I l to facilitate its being heated from the combustion portion l3. Although both the temperature of the fuel at the pump inlet and the suction pressure within the chamber 84 determine the degree of fuel vaporization, the vaporization of the fuel is facilitated by increasing the temperature of the fuel rather than by increasing the degree of suction pressure. In other words fuel at 180 F. will vaporize at five inches of mercury more readily than fuel at a temperature of 80 F. at a vacuum pressure ofseven inches of mercury. B heating a portion of the fuel line '46, therefore, the vapor lock condition in the pump 43 is made more immediatel responsive to the heat condition in the combustion chamber I3, so

, as to appreciably reduce the period of lag between the occurrence of the vapor lock condition and the degree of heat applied to the system.

, por lock condition in the pump can result from a heatin of the pump to in turn heat the fuel therein, heating of the fuel alone prior to its entering the pump, or by the heating of both the pump and the fuel line. The cooling fluid for 'maintaining a normal operation of the fuel system can effect a vapor lock condition in the pump by its becoming heated above a temperature adapted to retain such normal operation, or by a complete stoppage thereof. It is obvious of course that the invention is not restricted to the solenoid 9 pump illustrated, but it is applicable for use with any pump which operates with a suction and working cycle.

Although the invention has been specifically described with reference to a preferred embodiment thereof it is to be understood that it is not so limited since modifications and alterations can be made therein which are within the full intended scope of the invention as defined by the appended claims.

I claim:

1. In a heater which includes a heat exchange structure defining a fuel combustion chamber; a liquid fuel supply system for delivering fuel to said combustion chamber, means for vaporizing a portion of the fuel traversing said system as the temperature of said structure rises above a given value, and means included in said system for delivering combustible fuel to said combustion chamber at a mass rate which gradually decreases with increase in the rate of vaporizing of said fuel by said last-named means.

2. In a heater which includes a heat exchange structure defining a fuel combustion chamber; a liquid fuel supply system for delivering fuel to said combustion chamber, means for vaporizing the fuel traversing said system at a rate which increases as the temperature of said structure increases from a given value, and means included in said system for delivering combustible fuel to said combustion chamber at a mass rate which varies inversely with the rate at which the fuel is vaporized by said last-named means.

3. In a heater which includes a heat exchange structure defining a fuel combustion chamber; a liquid fuel supply system for delivering fuel to said combustion chamber, means including parts of said structure and parts of saidsystem arranged in heat transferrrelationship for utilizing the heat of fuel combustion within said chamber to vaporize a portion of the fuel traversing said system as the temperature of said structure rises above a given value, and means included in said system for delivering combustible fuel to said chamber at a mass rate which gradually decreases with increase in the rate of vaporizing of said fuel by said last-named means.

4. In a heater which includes a heat exchange structure defining a fuel combustion chamber; a liquid fuel supply system for delivering fuel to said combustion chamber, means including parts of said structure and parts of said system arranged in heat transfer relationship for utilizing the heat of fuel combustion within said chamber to vaporize a portion of the fuel traversing said system as the temperature of said structure rises above a given value, means included in said system for delivering combustible fuel to said chamber at a mass rate which gradually decreases with increase in the rate of vaporizin of said fuel by said last-named means, and means for circulating air through at least one heat transfer zone between said structure and said system, thereby to prevent the vaporization of the fuel traversing said system until the temperature of said structure exceeds said given value. p

5. In a heater which includes a heat exchange structure defining a fuel combustion chamber; a

liquid fuel supply system for delivering fuel to said combustion chamber, means including parts of said structure and parts of said system arranged in heat transfer relationship for utilizing the heat of fuel combustion within aid chamber to vaporize the fuel traversing said system at a rate which increases as the temperature of said structure increases from a given value, and means included in said system for delivering combustible fuel to said combustion chamber at a mass rate which varies inversely with the rate at which the fuel is vaporized by said last-named means.

6. In a heater which includes a heat exchange structure defining a fuel combustion chamber, a liquid fuel supply system for delivering fuel to said combustion chamber, means including parts of said structure and parts of said system arranged in heat transfer relationship for utilizing the heat of fuel combustion within said chamber to vaporize the fuel traversing said system at a rate which increases as the temperature of said structure increases from a given value, means included in said system for delivering combustible fuel to said combustion chamber at a mass rate which varies inversely with the rate at which the fuel is vaporized by said last-named means, and means for circulating air through at least one heat transfer zone between said structure and said system, thereby to prevent substantial vaporization of the fuel traversing said system until the temperature of said structure exceeds said given value.

7. In a heater which includes a heat exchange structure defining a fuel combustion chamber; a liquid fuel pump and a conduit fluid connected with the inlet side of said pump, means including a part of said structure and a portion of said conduit arranged in heat transfer relationship for utilizing the heat of fuel combustion within said chamber to heat the fuel traversing said conduit and thus produce at least partial vaporization of said fuel within said pump, and means comprising said pump for delivering combustible fuel to said combustion chamber at a mass rate which gradually decreases with increase in the rate of vaporizing of said fuel within said pump.

8. In a heater which includes a heat exchange structure defining a fuel combustion chamber; a liquid fuel pump and a conduit fluid connected with the inlet side of said pump, means including a part of said structure and a portion of said conduit arranged in heat transfer relationship for utilizing the heat of fuel combustion within said chamber to heat the fuel traversing said conduit and thus produce at least partial vaporization of said fuel within said pump, means comprising said pump for delivering combustible fuel to said combustion chamber at a mass rate which gradually decreases with increase in the rate of vaporizing of said fuel within said pump, and means for circulating air through the zone of heat transfer between said part of said structure and said portion of said conduit, thereby to prevent substantial vaporizing of the fuelwithin said pump until the temperature of said structure exceeds a predetermined value.

HARRY B. I-IOLTI-IOUSE. 

